1. Field of the Invention
The present invention relates to an image determining method and an object coordinate computing apparatus, and particularly relates to an image determining method and an object coordinate computing apparatus, which utilize both brightness and conditions besides brightness to determine the predetermined image pixel or the object pixel.
2. Description of the Prior Art
FIG. 1 is a schematic diagram illustrating a prior art image determining method for determining an object coordinate in an image. FIG. 1 is a gray level diagram of an image (i.e. an brightness diagram of an image), which is a 7×8 matrix having 7×8 pixels P11-P78. The image includes a specific image generated by an object (in this example, a light source). Specific image pixels for this specific image have higher brightness values than the pixels surrounding them, for examples, pixels P16, P25-P27, P34-P38, P43-P48, P54-P57 and P65-P67.
One of the methods for determining the specific image pixels is determining the pixels having brightness values higher than a threshold value as specific image pixels. In the example shown in FIG. 1, the threshold value is gray level 100, such that the pixels P26, P35-P37, P44-P47, and P55-P56 will be determined to be specific image pixels. However, the edge pixels for the specific image have lower brightness values, thus such determining method still determines the pixels P16, P25, P27, P34, P38, P43, P48, P54, P57 and P65-P67 to be normal pixels rather than specific image pixels. If the threshold value is adjusted to be lower, such as 80, normal pixels P75 and P76 will be determined to be specific image pixels, but still exclude the pixel P16. Also, the size, location and brightness values of different specific images caused by different objects are all different, thus a most suitable brightness threshold value is hard to select.